A cylinder head cover generally made of a plastic material, in comparison with a metallic cylinder head, is fastened onto a cylinder head by using a plurality of locking bolts.
The plastic cylinder head cover is advantageous both in reducing weight of the engine and in improving ease of manufacture of the cylinder head cover. However, there is a drawback in that rigidity of holes for coupling the locking bolts is inadequate and the processing accuracy is relatively low.
Accordingly, in order to attain a sufficient rigidity for holes formed at the plastic cylinder head cover, bushings made of steel are inserted into the cylinder head cover to be fastened with the locking bolts.